Drive and control system for electric automobiles

ABSTRACT

A drive and control system for electrically powered automobiles. Controlled rectifiers are connected between a battery and the armature circuit of a compound motor to supply increasing amounts of current to the armature for acceleration. Transistors are connected between battery and shunt field to control current thereto. An accelerator pedal connected to a carbon pile resistor controls the conduction of the transistors. Relays connect the battery directly to the shunt field for starting, and control the sequence in which increasing amounts of current are supplied to the armature. A charging circuit permits charging of the main battery from a conventional AC source. A switch is provided to allow connection of the motor as a generator for charging the battery when the vehicle is towed or pushed. Motors and associated switches and relays may be provided to control and operate an automatic clutch in conjunction with the drive and control system.

United States Patent [72] Inventor William H. Lee

505 North Lake Shore Drive 01306, Chicago, 111. 60611 [21 Appl. No.2,124

[22] Filed Jan. 12,1970

[45] Patented Dec. 21, 1971 [54] DRIVE AND CONTROL SYSTEM FOR ELECTRICAUTOMOBILES 9 Claims, 6 Drawing Figs.

[52] US. Cl 180/65 R, 318/139 [51] Int. Cl B601 11/18, B601 15/12 [50]Field of Search 180/65; 7 318/139; 105/50 [56] References Cited UNITEDSTATES PATENTS 3,1 14,871 12/1963 Schenkelberger 180/65 X 3,182,7425/1965 Dow 180/65 X 3,190,387 6/1965 Dow 180/65 3,349,309 10/1967Dannettell 318/139 X l5 ELECWC DR/VE MAM M0705, cu/mv ./8 l2 3 I M070?CONT/50L MAW am/(Es BATT A [Jewe 's/ AFT A 0 u/ss/o/v WHEEL 5 3,454,1227/1969 Grady,.lr. 180/65 FOREIGN PATENTS 1,074,443 7/1967GreatBritain..' 180/65 Primary Examiner- Benjamin Hersh AssistantExaminerMilton L. Smith A tt0rney-Bosworth, Sessions, Herrstrom & Cain Ifor acceleration. Transistors are connected between battery and shuntfield to control current thereto. An accelerator pedal connected to acarbon pile resistor controls the conduction of the transistors. Relaysconnect the battery directly to the shunt field for starting, andcontrol the sequence in which increasing amounts of current are suppliedto the armature. A charging circuit permits charging of the main batteryfrom a conventional AC source. A switch is provided to allow connectionof the motor as a generator for charging the battery when the vehicle istowed or pushed. Motors and associated switches and relays may beprovided to control and operate an automatic clutch in conjunction withthe drive and control system.

PATENIEIJ new m1 SHEET 2 OF 3 A TTOR/VEYS DRIVE AND CONTROL SYSTEM FORELECTRIC AUTOMOBILES BACKGROUND OF THE INVENTION This invention relatesto controls for electric motors and more particularly to a drive andcontrol system for an electrically powered automobile.

Electrically powered automobiles have recently acquired increasedsignificance because of the advantage they offer of not contributing tothe existing-levels of air pollution. The problems associated with theiruse have not heretofore been overcome to an extent sufficient to allowthem to achieve significant public acceptance. The chief reason fortheir general lack of acceptance is their reduced-level of performancecompared to conventional automobiles.

The lower level of performance occurs specifically in reduced drivingrange and relatively poor, unsmooth acceleration. Prior control systemshave contributed to both of these problems, to the first because thesystems themselves consumed a significant amount of battery power, andto the second as a consequence of the designs.

SUMMARY OF THE. INVENTION A general object of this invention is theprovision of a drive and control system for electrically poweredautomobiles that overcomes the problems noted above encountered withprior control systems. More particular'objects are the provision of anelectrical drive and control system that provides smooth operation andacceleration and that may be employed on automobiles having a manuallyoperated clutch and conventional transmission or on automobiles havingan automatic clutch and conventional transmission.

Another object of this invention is the provision of a control systemthat consumes very little power.

Still another object is the provision of a drive and control system thatemploys the energy developed in regenerative braking to charge the mainbattery.

Other objects are the provision of a drive and control system thatincludes means for charging the main battery easily and conveniently atevery opportunity and that includes means for allowing the electricdrive motor to be operated as a generator when the automobile is towedor pushed thereby to charge the main battery.

Yet another object is the provision of an electrical circuit forcontrolling and operating an automatic hydraulic clutch in anelectrically powered automobile.

A preferred embodiment of this invention comprises a battery, a motorhaving an armature and a shunt field, and electronic switching means forconducting varying amounts of current to the armature. First controlmeans is provided for causing the switching means to conduct limitedamounts of current to the armature. Second control means is providedhaving a first state operative to connect the battery directly to thefield, and a second state determined by the armature voltage of themotor operative to initiate full conduction by the switching means.Transistor means is provided to control current to the field during thesecond state of the second control means. A variable resistor operatedas an accelerator controls the conduction of the transistor means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the basicportions of an electrically powered automobile having a conventionaltransmission and manual clutch.

FIG. 2 is a block diagram similar to FIG. I in which the electricallypowered automobile has an automatic hydraulic clutch operated by anelectrical clutch control circuit according to this invention FIG. 3 isa schematic diagram of a preferred embodiment of the basic drive andcontrol system according to this invention.

FIG. 4 is a schematic diagram of a preferred embodiment of batterycharging circuit for use in conjunction with the basic drive and controlsystem of FIG. 3.

FIG. 5 is a schematic diagram illustrating a preferred circuit for a"low" mode in which the motor is operated as a generator to charge themain battery when the automobile is being towed or pushed.

FIG. 6 is a schematic diagram of a preferred clutch control circuitemployed with the basic drive and control system on an automobile havingan automatic hydraulic clutch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. I, the basiccomponents of an electrically powered automobile employing thisinvention include a main battery I0 which supplies power to a drivemotor 11 through a motor control circuit 12. Motor 11 is connected to aconventional manual transmission 14 through a manual clutch 15.Transmission 14 transmits power to the drive shaft and wheels asindicated at 16 and is controlled by manual gearshift level 17. Anaccelerator pedal 18 connected to the motor control circuit allows theoperator to vary the speed of the automobile as will be explained morefully hereinafter. A conventional brake pedal 19 is provided to operateconventional brakes 20.

In FIG. 2 the electrically powered automobile has an automatic hydraulicclutch 15 that connects motor 11 to conventional manual transmission 14.In the electrically powered automobile the conventional mechanical meansdriven by the internal combustion engine for operating the automaticclutch is not present, but instead an electrical clutch control circuit22 is provided for controlling and operating the automatic clutch. Theclutch control circuit 22 is operated through the gearshift level 17,the accelerator pedal 18 and the brake pedal l9 and controls a vacuumpump 23 and a hydraulic pressure pump 24 which operate the automaticclutch, all of which will be explained more fully hereinafter.

Referring now to FIG. 3, the drive portion of the drive and controlsystem of this invention comprises battery I0 and motor 11 which has anarmature 26 and a shunt field 27. Motor 11 is preferably of the compoundtype having a series field 28 in addition to shunt field 27. Theterminal voltage of battery It] is preferably on the order of 120 volts.Battery 10 may comprise several batteries in series and should have ahigh-ampere-hour capacity and be suitable for repeated recharging.

The remainder of the circuit in FIG. 3 controls the transfer of powerfrom battery 10 to motor 11 to provide smooth and trouble-free operationfor both city and highway driving. The circuit of FIG. 3 may be used inan electrically powered automobile having either a manual clutch or anautomatic hydraulic clutch as shown in FIGS. 1 and 2 respectively.

The control system of FIG. 3 may be regarded as having three principlecircuits shown bounded by dashed lines. These circuits are an armaturecurrent control circuit 29, a field current control circuit 30 and anenabling and starting circuit 3!. It will be appreciated, however, thatthe different circuits cooperate and interact so that no hard and fastdivision of circuits is possible. In general, the armature currentcontrol circuit 29 functions to control the amount of current suppliedto the armature 26 of motor 11 in steps until full conduction isreached. The field current control circuit 30 is operative to controlthe amount of current supplied to the shunt field winding 27 duringhigher speed operation but connects the battery 10 directly to the shuntfield winding 27 for starting.

The enabling and starting circuit 31 comprises an enabling switch 32which is analogous to the ignition switch in a conventional automobile,a starting switch 33 and relays 35 and 36. Actuating starting switch 33does not, in itself, start motor 11 but initiates a sequence of eventswhich results in starting as will be explained below. Relay 35 isprovided with normally Armature current control circuit 29 comprisessilicon controlled rectifiers 37 and 38 connected to armature 26 throughseries resistors 40 and 41, respectively, and a third silicon controlledrectifier 42 connected directly between battery and armature 26. A relay43 having normally open contacts 43a and 43b, the latter being shown infield current control circuit 30, is connected to be energized throughcontact 36b of relay 36. Another relay 45 having normally open contacts45a and 45b and normally closed contacts 450 and 45d is connected to beactuated when the voltage across armature 26 and series field 28 reachesa predetermined value. Contacts 45b and 45d are in field current controlcircuit 30 while contact 45c is in enabling and starting circuit 31. Aconventional semiconductor diode 47 is connected in inverse parallelwith controlled rectifier 42 for a purpose to be described hereinafter.

The shunt field current control circuit 30 comprises paralleltransistors 49 and 50 connected to shunt field winding 27 throughemitter resistors 51 and 52 respectively. The bases of the twotransistors are connected in parallel and are controlled by a circuitcomprising tungsten filament bulb 54, re sistor 55, contact 43b of relay43 and variable resistor 57. Variable resistor 57 is preferably a stackof carbon wafers or carbon pile, the resistance of which is decreased byincreasing pressure forcing the carbon wafers together. Variableresistor 57 is preferably controlled by accelerator pedal 18, asindicated by the dashed line between them, to vary the voltage level atthe bases of transistors 49 and 50 and, therefore, the amount of currentsupplied to field winding 27. A diode 58 is connected across fieldwinding 27 to prevent high inverse voltage due to rapid decrease infield current by providing a field current discharge path.

A normally closed contact 45d of relay 45 is connected acrosstransistors 49 and 50 to connect battery 10 directly to shunt fieldwinding 27 during starting of motor 11 as will be explained more fullyhereinafter. Also connected across transistors 49 and 50 is a tungstenbulb 59 which, because its resistance varies directly with the voltage,tends to maintain a minimum supply of current of field winding 27. Thepath for current through shunt field winding 27 is completed throughcontact 36a or contact 45b as will be explained below.

Operation of an electrically powered automobile containing the drive andcontrol system according to this invention is initiated by closing theenabling switch 32 and momentarily depressing starting switch 33 toenergize relay 35 which locks in through normally open contact 35a.Depressing accelerator pedal 18 decreases the resistance of resistor 57allowing relay 36 to be actuated through contacts 35b. Relay 36 locks inthrough contacts 36a and normally closed contacts 450 of relay 45.

Upon actuation of relay 36 contacts 36b allows a positive signal toappear at the gate of controlled rectifier 37 which thereupon conductscurrent through resistor 40 to armature 26 of motor 11. Closing ofcontact 361) likewise causes actuation of relay 43 and the closing ofcontacts 43a which in turn triggers controlled rectifier 38 intoconduction to also supply current to armature 26 through resistor 41.Relay 43 is preferably of the time delay type so thatgradualacceleration may occur in response to the current supplied throughcontrolled rectifier 37 before controlled rectifier 38 is triggered intoconduction by relay 43.

When the voltage across the armature and series field or motor 11reaches a predetermined value, relay 45, which is a voltage controlledrelay, is actuated causing the gate of controlled rectifier 42 to betriggered through contacts 45a so that controlled rectifier 42 conductsfull current to armature 26, shutting off controlled rectifiers 37 and38.

While motor 11 is accelerating, shunt field winding 27 is connecteddirectly to battery 10 through normally closed contact 45d of relay 45.

Actuation of relay 45 opens contacts 4511 to allow transistors 45 and 50to control the current supplied to field winding 27, opens contacts 450to interrupt that hold path for relay 36 and closes contacts 45b toprovide another path to ground for current flowing in field winding 27in addition to the path through contact 360. Relay 36 now holds throughcontact 35b and resistor 57. Releasing accelerator pedal 18 willincrease the resistance of resistor 57 and cause relay 36 to drop out.In such case, current through field winding 27 will still have a path toground through contact 45b. The circumstances under which acceleratorpedal 18 will normally be released will be explained below.

To summarize the theory of operation, since motor torque is directlyproportional to the flux and to the armature current these are maximizedat starting when high torque is desired. During higher speed driving theshunt field current is varied to vary the speed of the automobile sincethe motor r.p.m. varies inversely with the flux, which depends upon thefield current.

Operation of the electrically powered automobile having a manual clutchand transmission is now virtually the same as operation of aconventional automobile. Depressing accelerator pedal 18 decreases theresistance of resistor 57 which lowers the voltage at the bases oftransistors 49 and 50 thereby reducing the current supplied to fieldwinding 27 which in turn causes motor 11 to accelerate. By manipulatingaccelerator pedal 18 and using the conventional clutch and transmission,operation of the vehicle proceeds in much the same manner as with aconventional automobile.

When accelerator pedal 18 is released, as for example, when braking orotherwise decelerating, relay 36 is deenergized which in turndeenergizes relay 43 and causes contact 4312 to open. The resultingincrease in the voltage level at the base of transistors 49 and 50causes a large increase in the current supplied to shunt field winding27 which in turn causes motor 11 to regenerate and supply current tocharge battery 10 through diode 47. As the automobile is being braked toa stop, regenerative current flow through diode 47 to charge battery 10continues until the armature voltage of motor 11 is no longer sufficientto cause such current flow. Thereupon relay 45 opens and the sequence ofoperation will begin anew when accelerator pedal 18 is again depressed.

If, on the other hand, the automobile is accelerated by depressingaccelerator pedal 18 before relay 45 is allowed to release, relay 36will be actuated which will in turn actuate rely 43. During the slowoperating time of relay 43 controlled rectifier 37, having beentriggered through contact 36b, conducts current to armature 26. Whenrelay 43 is fully actuated, contacts 43b will close reducing the currentsupplied to field winding 27 and triggering controlled rectifier 42again into conduction so that normal operation resumes.

During normal operation minimum current to shunt field winding 27 andtherefore maximum speed and acceleration is determined by tungstenfilament bulbs 54 and 59.

The customary automobile accessory battery 61 is connected in serieswith the field winding 27 to be charged by the current flowing throughfield winding 27. The automobile lights 62 and horn 63 are connectedacross the accessory battery 61 so that they may be supplied from theaccessory bat tery 61 or by current flowing through field winding 27.

Smoothness of operation is greatly enhanced by carbon pile resistor 57which allows the field current to be continuously rather thanincrementally varied, and by emitter resistors 51 and 52, the emitterresistors providing a measure of negative feedback which providessmoother current flow in transistors 49 and 50 and smootheracceleration. Power consumption in the control circuit is minimizedsince only a small current in carbon pile resistor 57 is needed tocontrol the much larger current in field winding 27, and the relaysconsume little power. The control system of this invention thus controlsthe speed and acceleration of an electrically powered automobileeffectively and efficiently without the excessive power consumption andjerky operation characteristic of some prior systems.

FIG. 4 shows a charging circuit by which battery 10 can be charged froma normal l20-volt line at every opportunity. The circuit is equippedwith a power cord terminating in a conventional male plug 65 one pin ofwhich may be grounded. When plug 65 is connected to a suitable source ofAC power a conventional AC relay 66 is actuated closing contacts 66a and66b and openings contact 660. The contacts of relay 66 operate todisconnect battery from the normal automobile ground through contact 660and connect it to the negative output terminal of rectifier 68 throughcontact 66b. Alternating current is rectified by bridge circuit 68 andthe rectified current charges battery 10, the rate of charge beingindicated by ammeter 69, which includes shunt 70.

An ampere-hour meter 71 serves as a fuel gauge" monitoring the state ofcharge of battery 10. Ampere-hour meter 71 integrates current and timeso that current flowing out of battery 10 for a particular amount oftime causes the indicator of meter 71 to move a certain amount in onedirection while the same amount of current flowing into battery 10 forthe same time will cause the indicator to return nearly to its originalposition. Meter 71 is preferably calibrated in terms of the ampere hourcapacity of battery 10.

Referring now to FIG. 5 there is illustrated schematically a circuit bywhich motor 11 may be employed as a generator to charge battery 10 whenthe automobile is being pushed or towed. The major portion of FIG. 5 isidentical to FIG. 3. The only change is the addition of run-tow switch73 which disconnects shunt field winding 27 from emitter resistors 51and 52 of transistors 49 and 50 and connects the winding directly acrossarmature 26 and series field 28 of motor 11. This connection allowsmotor 11 to be operated as a differential compound generator, chargingbattery 10 through diode 47 when the automobile is pushed or towed.

As noted above, it is intended that the drive and control system ofFIGS. 1 to 5 may be employed in automobiles having an automatichydraulic clutch as shown in FIG. 2. in FIG. 6, electrical means forcontrolling and operating the automatic clutch in conjunction with thedrive and control system of this invention are shown schematically.

Referring to FIGS. 2 and 6 relay 35 corresponds to relay 35 in FIG. 3,but is a lower voltage relay actuated from the nor mal accessory battery61. A motor driven vacuum pump 23 and a motor driven hydraulic pressurepump 24 (FIG. 2) are supplied to provide vacuum and hydraulic pressureto operate the clutch. Motors 75 and 76 drive vacuum pump 23 andpressure pump 24 respectively. A pressure switch 77 opens to deenergizevacuum pump motor 75 when vacuum is sufficient. A solenoid valve 78initiates clutch release when energized. A relay 80 having normally opencontacts 80a and 80b and normally closed contacts 80c and 80d isactuated through a switch 81 and its own contact 800 and holds throughits own contact 80a and a normally closed switch 83. Switch 83 isactuated by accelerator pedal 18. as indicated by the dashed linetherebetween. Switch 81 is actuated by brake pedal 19 as indicated bythe dashed line. A normally open switch 84 which is actuated momentarilywhenever manual gear shift 17 is manipulated also operates solenoidvalve 78 to initiate release of the clutch.

Operation of the electrically powered automobile with an automaticclutch is essentially the same as with a manual clutch except for theobvious differences due to having the automatic clutch. Starting isinitiated by closing enabling switch 32 and momentarily depressingstarting switch 33 which actuates relay 35'. Relay 35 holds in throughits normally open contact 35aand allows actuation of relay 36 (FIG. 3)when accelerator pedal 18 is depressed. The sequence of operation thencontinues as explained above in connection with FIG. 3.

For hydraulic clutch operation clutch release solenoid valve 78 isactuated to release the clutch in either of two ways. Manipulation ofmanual gear shift 17 momentarily closes switch 84 and actuates solenoidvalve 78, or actuation of relay 80 energizes solenoid valve 78 throughcontact 80b.

Relay 80 is actuated by depressing brake pedal 19 which closes switch 81and energizes relay 80 through its own contact 80:. So long as relay 80remains actuated, clutch release solenoid valve 78 remains actuatedthrough contact 80b and power is removed from pressure pump motor 76 bycontacts 8%. Relay tit remains actuated through its own contact a andnormally closed switch 83 actuated by accelerator pedal lib. Whenaccelerator pedal 18 is depressed to accelerate the automobile, switch83 opens and relay 8t) releases causing the clutch to reengage.

in summary, the hydraulic clutch is released by manually shifting gears(switch 84) or by depressing the brake pedal 19 (switch S1). The clutchis reengaged in the former case by completing the act of shifting gearsand in the latter case by depressing accelerator pedal .18.

While the clutch control circuit of FIGS. 2 and 6 is advantageously usedin conjunction with the basic drive and control system of FIG. 3 it willbe apparent to those skilled in the art that the clutch control circuitmay be used in automobiles independently of the basic drive and controlcircuit.

In the description of the drive and control system for electricallypowered automobiles encompassing FIGS. 1 and 6, circuit breakers, fusesand similar'circuit devices not necessary for the description ofoperation have been omitted from the drawings and from the discussion.Such devices may, of course, be supplied by those skilled in the art.

While there has been shown and described one illustrative embodiment ofthis invention, it is to be understood that the concepts thereof couldbe employed in other embodiments without departing from the spirit andscope of the invention.

What is claimed is:

1. A drive and control system for an electrically powered automobilecomprising, a motor having an armature and a shunt field, a battery forsupplying power to said motor, electronic switching means between saidbattery and said armature for conducting varying amounts of current tosaid armature, first control means for initiating conduction by saidswitching means of a limited amount of current to said armature, secondcontrol means having a first state operative to connect said battery tosaid field and a second state determined by the armature voltage of saidmotor operative to initiate full conduction by said switching means,transistor means operative to control current to said shunt field duringthe second state of said second control means, and means for controllingthe conduction of said transistor means.

2. The system of claim 1 further comprising a rectifier connected acrosssaid switching means to allow charging of said battery duringregenerative operation of said motor.

3. The system of claim 2 further comprising a switch for connecting saidshunt field directly across said armature, whereby said motor mayoperate as a generator to charge said battery through said rectifierwhen said automobile is towed.

4. The system of claim 1 further comprising means for charging saidbattery from an AC source external to said automobile, said meanscomprising conductor means for conducting current to said battery, aconnector for connecting said conductor means to a source of AC power, arectifier for rectifying the current flowing to said battery, and relaymeans operative upon connection of said connector to said AC source toconnect said battery to the output of said rectifier.

5. The system of claim 1 further comprising switch means for controllingsaid first control means to thereby initiate operation of said drive andcontrol system.

6. The system of claim 1 wherein said second control means has anormally closed condition bypassing said transistor means for connectingsaid battery to said shunt field and a normally open condition forsupplying a signal to said switching means upon actuation of said secondcontrol means, said signal initiating full conduction of said switchingmeans.

7. The system of claim 1 further comprising a tungsten filament bulbconnected across said transistor means to conduct a minimum current tosaid shunt field, whereby the maximum speed of said automobile isdetermined.

8. The system of claim 1 wherein said means for controlling theconduction of said transistor means comprises a variable resistorcoupled to the base of said transistor means and an accelerator pedalconnected to said resistor for varying the resistance thereof, wherebypressure applied to said accelerator pedal varies the amount ofconduction of said transistor means.

9. The system of claim 1 wherein said switching means comprises at leastone controlled rectifier having a resistance in, series therewithcoupled to said armature, and another con- 5 trolled rectifier coupleddirectly to said armature.

1. A drive and control system for an electrically powered automobilecomprising, a motor having an armature and a shunt field, a battery forsupplying power to said motor, electronic switching means between saidbattery and said armature for conducting varying amounts of current tosaid armature, first control means for initiating conduction by saidswitching means of a limited amount of current to said armature, secondcontrol means having a first state operative to connect said battery tosaid field and a second state determined by the armature voltage of saidmotor operative to initiate full conduction by said switching means,transistor means operative to control current to said shunt field duringthe second state of said second control means, and means for controllingthe conduction of said transistor means.
 2. The system of claim 1further comprising a rectifier connected across said switching means toallow charging of said battery during regenerative operation of saidmotor.
 3. The system of claim 2 further comprising a switch forconnecting said shunt field directly across said armature, whereby saidmotor may operate as a generator to charge said battery through saidrectifier when said automobile is towed.
 4. The system of claim 1further comprising means for charging said battery from an AC sourceexternal to said automobile, said means comprising conductor means forconducting current to said battery, a connector for connecting saidconductor means to a source of AC power, a rectifier for rectifying thecurrent flowing to said battery, and relay means operative uponconnection of said connector to said AC source to connect said batteryto the output of said rectifier.
 5. The system of claim 1 furthercomprising switch means for controlling said first control means tothereby initiate operation of said drive and control system.
 6. Thesystem of claim 1 wherein said second control means has a normallyclosed condition bypassing said transistor means for connecting saidbattery to said shunt field and a normally open condition for supplyinga signal to said switching means upon actuation of said second controlmeans, said signal initiating full conduction of said switching means.7. The system of claim 1 further comprising a tungsten filament bulbconnected across said transistor means to conduct a minimum current tosaid shunt field, whereby the maximum speed of said automobile isdetermined.
 8. The system of claim 1 wherein said means for controllingthe conduction of said transistor means comprises a variable resistorcoupled to the base of said transistor means and an accelerator pedalconnected to said resistor for varying the resistance thereof, wherebypressure applied to said accelerator pedal varies the amount ofconduction of said transistor means.
 9. The system of claim 1 whereinsaid switching means comprises at least one controlled rectifier havinga resistance in series therewith coupled to said armature, and anothercontrolled rectifier coupled directly to said armature.